Doomed Russian Mars Probe Just Hours From Crashing to Earth

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A botched Russian Mars probe is just hours away from a fiery doom
when it plunges into Earth's atmosphere in a fatal crash. It
won't fall over the United States, but may crash into the
Atlantic Ocean, Russian space officials said today (Jan. 15).

The spacecraft, Russia's
Phobos-Grunt Mars moon probe, has been stranded in Earth
orbit since its November launch due to an engine failure that
prevented it from beginning its journey to the Red Planet. The
probe may fall any time between 12:50 p.m. EST and 1:34 p.m. EST
(1750 to 1834 GMT), with a potential crash zone in the Atlantic,
west of northern Africa, but exactly where the spacecraft will
crash is still uncertain, Russian Federal Space Agency
(Roscosmos) officials said in a statement.

According to the latest prediction from Roscosmos, the final
orbit of Phobos-Grunt will pass over southern South America,
Asia, southern Europe and parts of Africa. North America,
including the United States and Canada, Central America and
Australia are in the clear, since the Mars probe will not be
flying over those regions, according to the
latest crash zone map.

"About two hours out, the U.S. military will publish their last
re-entry prediction, and that will likely be the most accurate
public prediction, as they have very accurate data on the
object's orbit that will not be available publicly," Brian
Weeden, a technical adviser with the Secure World Foundation and
a former orbital analyst with the Air Force, told SPACE.com in an
email. "Up until then, I would take any prediction with a large
grain of salt." [ Infographic:
The Fall of Russia's Doomed Phobos-Grunt ]

Russian space officials have said that between 20 and 30 pieces
of Phobos-Grunt could survive re-entry and hit the Earth. In all,
about 440 pounds (200 kilograms) of the spacecraft is expected to
survive.

The Phobos-Grunt spacecraft is huge, weighing about 14.5 tons,
but most of that mass is contained in its fuel tanks, which are
filled with tons of toxic rocket propellant that was supposed to
be used on the trip to Mars. Russian and U.S. space officials
have said the fuel
tanks should burst during re-entry, allowing the fuel
to burn up before reaching the ground.

The probe is also carrying Yinghuo-1, China's first Mars orbiter,
which was hitching a ride to the Red Planet with Phobos-Grunt.

Russia launched the $165 million Phobos-Grunt on Nov. 9 Moscow
time (Nov. 8 EST) on a mission to collect samples from Mars'
largest moon Phobos and return them to Earth. The probe has a
cone-shaped sample return capsule that was designed to survive a
plunge through Earth's atmosphere in order to deliver the Mars
moon samples.

Ocean crash likely

Since most of the Earth's surface is covered by water, there is a
large chance that Phobos-Grunt will crash into an ocean. Previous
Roscosmos predictions have placed the point of impact in the
Indian Ocean, southern Atlantic and southern Pacific oceans, but
the space agency's latest estimate from today does not pinpoint
an estimated crash zone.

"ESA experts now expect Phobos-Grunt to re-enter in the late
afternoon/early evening (CET) of 15 January 2012, with an
uncertainty of +/- 4 hours," ESA space debris experts wrote in a
statement.

And the space agencies aren't alone in their falling Mars probe
vigil.

"There are also a number of other entities that appear to be
monitoring Phobos-Grunt (the amateur observers, Aerospace,
Celestrak, etc) but they are almost all relying on the [tracking]
data that is made public by the US military, which is a lot less
accurate that the private data the US military, the Russians, or
ESA will be using to make their calculations," Weeden said.

Phobos-Grunt is the latest in a series of satellite falls in
recent months. In September, a defunct NASA satellite called the
Upper Atmosphere Research Satellite (UARS), fell to Earth after
two decades in space. That fall was followed by the old German
X-ray observatory ROSAT, which crashed to Earth in October. But
unlike Phobos-Grunt, which failed just after its launch, The UARS
and ROSAT satellites were already shut down after completing
long, successful missions.

Russia has also had to deal with falling
satellites in the past. In 1978, the Soviet spacecraft Cosmos
954, a nuclear-powered Radar Ocean Reconnaissance Satellite,
crashed in Canada's Northwest Territories after four months in
space. The crash scattered radioactive material across parts of
Canada's Great Slave Lake, northern Saskatchewan and Alberta, and
prompted a joint U.S.-Canadian clean-up operation.

Phobos-Grunt does have one instrument, a spectrometer, that
uses the radioactive Cobalt-57 as a component, but the amount of
material is extremely small (less than 10 micrograms) and
should not post a concern, according to Lev Zelenyi,
director of the Space Research Institute in Moscow and chairman
of the Russian Academy of Sciences’ Solar System Exploration
Board.

The loss of Phobos-Grunt was a major blow to Russia's space
program, which saw five failed space missions in 2011, including
the malfunctioning Mars probe. In December, Russian
president Dmitry Medvedev said those responsible for the failure
could face disciplinary action. The failure also prompted Zelenyi
to write an open apology letter to the public and other
scientists.